The invention relates to a bore head for boring holes having a substantial length. The bore head includes three cutting edges or members which are distributed about the circumference of a base member which also carries a plurality of guide rods. Boring heads of this type are known, for example, from German Patent Publication 2,556,977, particularly FIGS. 1 and 2 of said patent publication. German patent Publication 2,556,977; corresponds to U.S. Pat. No. 4,133,399; issued Jan. 9, 1979. These bore heads have been found to be rather reliable in practical application. However, one disadvantage of prior art bore heads calls for improvement in that the so-called veering off of prior art bore heads may be relatively substantial over the length of a bore. The subsequent machining of work pieces that have been bored or the bore of which has been enlarged becomes the more difficult the more the direction of the bore has veered off a central longitudinal bore axis.
German Pat. No. 2,057,512 discloses bore heads which comprise support and guide elements enabling the bore heads to adapt themselves to uneven bore hole walls. These support and guide elements are arranged in two planes in a tiltable manner whereby the planes extend perpendicularly to each other.
However, the prior art support and guide elements do not achieve a reduction in the so-called "veering off" of the bore relative to the longitudinal, central bore axis.